Fluid-pressure-operated gear shifter



May 9, 1939. H. N. DURHAM 2,157,323

FLUID-PRESSURE OPERATED GEAR SHIF'TER Filed June 1, 1956 2 Sheets-Sheet 1 I A w fi m mm Patented May 9, 1939 FLUlD-PBESSURE-OPERATED GEAR SHIITER Hobart N. Manley Park, Long Island, N. Y assignmto Vaco Products, Inc., Jersey City, 1.,

a corporation of Delaware Application June 1, 1936, Serial No.'82,81'l

Clalms.

The present invention relates to a novel and improved power operated gear shift transmission, and more particularly to a novel and improved power operated gear shifter particularly adapted for use withsynchronized transmissions.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims. 1

The invention consists in the novel parts, construction, arrangements, combinations and improvements herein shown and described. v

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings:

Figure l is a vertical section of the synchro- .nized, constant-mesh "transmissionof an autoview of an illustrative embodiment of the present invention; and

motive vehicle to which the power'gear'shifting apparatus of the present invention has been applied;

Figure 2 is a horizontal" fragmentary sectional Figure 3 is a similar'view of a modified form of the invention.

The present invention has for its object the provision of a novel and improved power-operated change-gear transmission particularly adapted for use with automotive vehicles. Another object of the invention is the provision of a novel and improved fluid-pressure operated gear shifting mechanism adapted for the power shifting of automotive synchronized, constant mesh transmissions which are commonly known as ther object of the invention is the provision of a power operated gear shifting device in which.

means are provided for positively permitting synchronizing of the gears before they are meshed, thereby eliminating clashing of the gears while shifting. Still another object of the invention is the provision of a novel and improved method of regulating the speed of operation of a fluid pressure operatedmotor which is suitable for'use as a power shifting motor.

In the power shifting devices heretofore com- .monly employed with automotivev transmissions of both nonesynchronized'and synchronized types it has been customary to provide a fluid pressure ioperated motor having a piston connected to the shifting forks, which piston is moved at a substantially constant rate to shift'the gears from one ratio position to another. With such shifting devices applied to the shifting of synchronized synchro-mesh". transmissions. A fur-.

transmissions the piston movinguniformly does not give a sufficient opportunity for complete synchronization of the transmission before complete meshing takes place, and either the gears clash on meshing, the synchronizing elements are overloaded, or the piston must operate with undue slowness, thus making the vehicle sluggish in operation. With the present invention, the gearshifting motor first quickly shifts the gears to neutral position, and then pauses slightly in synchronizing position, the period of pause being of sufficient length of time to allow complete synchronization of the gears, after which the gears are again quickly moved into another speed position.

The shifting motor of the present, invention may be applied to any of the-shifting forks so as to operate as the gears are shifted from any speed to any other speed position, but in three speed and reverse transmissions, the greatest need for the invention is in'connection with the shift from third speed into intermediate speed, and from first or low speed into second or intermediate description and the following detailed description as well, are exemplary and explanatory of the invention but are not restrictive thereof;

Referring now in detailto the illustrative embodiment of the present invention as shown in the accompanying drawings, the invention is shown asapplied to a conventional form of synchronized, constant-mesh automotive transmission in which a synchronizer is available for synchronizing= the positive clutches for second and third speed, with a lesser need for the definite synchrospeeds. As shown, the transmission, comprises a transmission housing in in which is rotatably journalled the driving shaft H, the driven shaft I2 and a counter shaft l3.. Driven shaft I2 is connected at one end to the universal joint i5 and by it to the propeller shaft (not shown), and at its other end is freely and rotatably mounted within the recessed end M of the driving shaft 1 l by means of the roller bearing l6.

I The driving shaft II is formed with a gear 20 and positive clutch teeth 2 I, the gear 20 meshing with one gear 23 of the multiple gear 22 which is freely rotatable on the counter shaft, l3, while the intermediate gear 21 of the gear 22 meshes with the second-speed gear 24 which is freely rotatable by means ofball bearings'25 on the driven shaft l2. Gear 24 is also formed with positive clutch teeth 26.

For first speed and reverse, a gear 33 is slidably splined to the driven shaft I 2, and is adapted to he slid into mesh with either the first speed gear 28 of the multiple gear 22 or with the reverse idler 3| meshing with the reverse portion 32 of the multiple gear 22.

Intermediate the clutch teeth 2| and 26 and slidable with respect thereto is an internally splined sleeve 35, slidable on splined collar 36 which in turn is splined to the forward end of the driven shaft l2. The splined sleeve 35 is externally grooved, as at 40, to receive the second and third speed shifter fork 4i which is mounted for sliding movement by means of the shift rod 42. As the shift rod is moved forwardly, the sleeve 35 positively locks the teeth 2| to the driven shaft i2 so that power is applied directly through the transmission, and all of the gears revolve idly. As the shift rod 42 is moved rearwardly, the sleeve 35 engages the teeth 26 so that power is transmitted from the driving shaft ll, through gears 20, 23, 21 and 24 to teeth 26 and through sleeve 35 to the splined driven shaft i2, at a reduced speed which is dependent upon the gear ratios employed. For shifting into and out of first speed and reverse, the gear 30 is formed with a groove 44 into which is fitted the first and reverse fork 45 slidably mounted by means of a shift rod 45.

Means are provided for synchronizing the intermediate and high speed clutches prior to their actual engagement, so as to avoid the clashing of these clutch teeth under many conditions of shifting gears, and for this purpose, the adjacent ends of the clutch members 2i and 25 are formed as clutch cones and 5i, adapted to engage with the correspondingly shaped internal clutch faces formed on the faces of splined collar 36. Means are also provided for forcing one or the other of the internal faces into engagement with the corresponding cone 50 or 5i as the sleeve 35 is slid forward or rearwardly, and for this purpose the collar 36 is provided with contained, and resiliently pressed balls which are urged into corresponding depressions on the inner face of the clutch sleeve 35, so that as the sleeve 35 is moved in either direction, the corresponding cone clutch is first engaged to speed up the driving shaft l l and its associated gears, after which the positive clutch is locked for driving.

Power means are provided for selectively shifting the gears so that power may be transmitted through any one of the sets of gears, and as embodied, these means comprise vacuum or suc tion operated, double-acting motors connected to the shift rods and selectively energized so that one or the other of the shift rods is moved in one direction or another, dependent upon the gear mesh desired by the operator of the vehicle.

Mounted on the transmission casing III are two double-ended cylinders and Si which may be duplicates of each other, although only the cylinder for second and third speed need be provided with means for slowing down the shifting action during the synchronizing period. Each of these cylinders is provided with a reciprocable piston 63 and piston rod 54 connected by depending arm to its respective shift rod. Thus the piston of cylinder 60 is connected by its arm 65 to rod 42, while the piston of cylinder 5! is connected to the shift rod 46, for the first speed and reverse gears.

The construction of the cylinder 60 is shown in detail in Figure 2 of the drawings and the piston 83 is mounted in the cylinder by means of its piston rod 64 which passes through suitable apertures in the end walls 65 and 51 of the cylinder. Suction may be applied to either end of the cylinder 60 by pipe 10 or II, or may be applied to the central portion of the cylinder (for neutral) through the neutral ports I2, and pipe 10 corresponds to second speed position, while pipe ll serves to apply suction for the movement of the piston and gears to high speed position.

In accordance with the illustrative embodiment of the invention, means are provided for selectively admitting air to one end or the other of the cylinder 60, dependent upon which end is subjected to suction, so that as suction is applied to one end of the cylinder, air is admitted to the other end of the cylinder to increase the pressure difference between the two faces of the piston 63. These means also serve to interrupt the admission of air to the cylinder end as the synchronizing clutches engage and thereby provide a definite pause in the piston stroke so that complete synchronization of the transmission may be obtained.

As embodied, the admission of rir is controlled by fluid pressure operated valves controlled in their operation by the application of suction to the other end of the cylinder and by the position of the piston in the cylinder. Each of these valves comprises a pair of valve chambers or cylinders 13 and 14 mounted on the side of the cylinder, and axially alined with each other.

At one end of the cylinder 60 is a duct 15 leading from the cylinder end to the valve seat at one end of the cylinder 14, which in turn communicates with the atmospheric duct 16 at one side of the cylinder under control of the frustro-conical end of the valve plunger H. The main body of the plunger 11 is cylindrical and is fitted within the cylinder 14 which at its other end communicates with the central portion of cylinder 60 through duct 19 so that the pressure in the corresponding portion of the cylinder is applied to the inner end of the plunger. Separating the cylinders 13 and i4 is a web having an aperture therein to receive the rod 8i connecting plunger I1 with the piston 83 which is fitted within the cylinder 13. Piston 83, plunger 1'! and rod 8i are all slidable within their respective cylinders and aperture, but are substantially tight therein so as to avoid excessive leakage.

The inner end of cylinder 13 is in communication with the central portion of the cylinder 60 through duct 85, while the outer end of the cylinder 13 is connected to the end of cylinder 60 by duct 81, and plunger 1 is normally held seated against the valve seat by means of the compression spring 88. Ducts i9 and 85 are spaced apart, preferably a distance only slightly more than the thickness of the piston 63, so that either one, but not both ducts, may be closed or restricted by the piston 63. The faces of piston 83 and the inner face of plunger 11 are open to pressure over substantially their whole area, while the reduced end of plunger 1! alone is subjected to the pressure applied through duct 15.

For admitting air to the other end of the cylinder a reversed duplicate of the fluid pressure controlled valving is provided, so that as suction is applied to either end of the cylinder 60 air is admitted to the other end under control of this suction and the position of the piston.

In the operation of this embodiment of the invention, as suction is applied to the cylinder through pipe II, and with the piston 63 at the right hand end of the cylinder 60 so that the 76 enemas gears are in second speed position, suction is also applied to faces 90, 9| and 92 of the piston 03- and plunger 11, and this force created by this suction exceeds the compression of spring 88 moving the plunger II to the left to admit air through ducts I5 and IE to the cylinder end. Thereupon, the piston 63 moves to the left until it closes off duct I9 and when the piston is in the position shown in Figure 2, the pressure on faces 92 and 03 is substantially equal, while the suction on faces 90 and 9| is substantially equal allowing the plunger II to close off duct I5 and thereby check the movement of piston 63 at the synchronizing point. Due to inevitable leakage, the piston 63 moves slowly to the left, finally uncovering port 85 and again unbalancing the pressures so that suction is applied only to face 00, while thepressure on the other faces SI, 92 and 93 is equal, again overcoming the force of spring 88 and opening the duct 15 to atmosphere to permit rapid movementof the piston 03 into third speed position. By suitably choosing the strength of spring 88 and the dimensions of the various parts, the synchronizing interval can be made as long as is desired for the particular conditions to be dealt with.

In shifting from third speed to second speed, the operation is the reverse of that just described; that is, the piston 63 moves from left to right, and the other set of automatic valves is in operation.

In the modified embodiment shown in Figure 3 of the drawings, the admission of air to either side of the piston 63 is controlled by a fluid pressure operated valve which is, in turn, controlled by a second fluid pressure operated valve operated in accordance with the fluid pressure at different be reversed duplicates of each other, one for each cylinder end.

As embodied, there is provided a valve chamber I00, at one side of the cylinder 60 in which is slidable a valve plunger I02 urged by spring I03 into position to close the communication between atmospheric ducts I5 and I6. A second valve chamber I05 is also mounted on the cylinder 50 and is provided with ducts I01, I08 and I leading directly to the interior of cylinder 60, and with duct I 06 connected chambers I and I00, and in this valve chamber is a double-ended plunger IIO, urged by spring III towards the right. Duct I06 communicates with the left end of chamber I00 and the central portion of chamber I05 andmay be closed by movement of the plunger I05 against the force of its spring III, while duct I09 comunicates with the left end of cylinder 00 and the central portion of chamber I051 Ducts I01 and I00 communicate with right and left'ends of chamber I05 and with the right and left sides of the piston 03 in neutral or synchronizing position.

when the valve H0 is in the position shown, suction applied to the left end of cylinder 00 may be applied through ducts I00 and I00 to the left end of plunger I02 to unseat the plunger with respect to duct I5 and thereby admit air to the right end of cylinder 50.

In the operation of the embodiment of Figure 3, suction is applied to the cylinder 00 through pipe II to move the piston from the right-hand end of cylinder 00 to the left as for shifting from second to third speed. This application of suc-.

tion, is transferred through duct I00 to duct I00 and to the left-hand end of plunger I 02 to unseat the plunger and open the duct I5 to atmosphere,

thereby admitting air through these ducts to the right end of cylinder 60. As the piston 63 moves to the left, duct I0! is closed and duct I08 remains open so that plunger IIO moves to the left as the suction is greater on its extreme left end than on its right end. This movement closes duct I06 and discontinues the suction on plunger I02 so that spring I00 will move plunger I02 to close duct I5. This closure of duct 15 slows the piston during the synchronization of the gears at this point in the piston travel, and thereafter on further movement of the piston 63, air is admitted through duct I08 allowing spring III to move plunger M0 to the right to open duct I05 and again allow suction to be applied to the left end of plunger I02. In this condition, the movement of the piston is accelerated, and the shifting rod 42 is quickly moved to its final position with the positive clutch fully meshed for driving engagemerit.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the in- Zention and without sacrificing its chief advanages.

What I claim is:-

1. In a fluid pressure operated motor, the combination of a cylinder havinga piston movable therein, a valve operated by the difference in pressure between two ends of the cylinder, means normally tending to close said valve when the pressure difl'erence is reduced, and means operated by the piston for momentarily minimizing the difference in pressure to close said valve.

2. In a suction motor, the combination of a cylinder having a piston movable therein, ducts for applying suction to one end and air to the other end of the cylinder, and means pneumatically controlled by the piston in its movement for momentarily closing one of said ducts to slow the piston in its movement.

3. In a fluid pressure operated motor, the combination of a cylinder having a piston movable therein, ducts connected with opposite ends of the cylinder to create different pressures on difl'erent sides of the piston, a valve operated by the pressure in one end of the cylinder and controlling the opening and closing of one of said ducts and a second valve controlled by the piston in certain positions for controlling the operation of the first valve.

\ 4. In a fluid pressure operated motor, the combination of a cylinder having a piston movable therein, ducts connected with opposite ends of the cylinder to create diiferent pressures on different sides of the piston, avalve operated by the pressure in one end ofthe cylinder and controlling the opening and closing of one of said ducts and a second valve operated by the differences in pressure on opposite sides of the piston in certain positions for preventing the application of pressure to the first valve for slowing the piston as it passes a predetermined point.

5. In a fluid pressure operated motor the combination of a cylinder having a piston movable therein, means operated by a change in pressure in one end of the cylinder for opening the other end oi the cylinder to atmosphere. and means operated by fluid pressure in said other end of the cylinder for preventing operation of said first means. Q

HOBART N. DURHAM. 

